Hydraulic actuator with arcuate expansible chambers

ABSTRACT

A fluid driving apparatus is contained in one of the ends of two lever arms designed to pivot about a common fulcrum point. The driving apparatus comprises a piston limited to move in a direction perpendicular to its axis, an arcuate expansible chamber in each of the lever arms, wherein each chamber is designed to receive one end of the piston, means for providing fluidic communication between the chambers and means for supplying fluid under pressure to the chambers thereby expanding said chambers and applying a force to the lever arms.

iJnited States atent [191 Kaesemeyer 1 Apr. 3, 1973 [54] HYDRAULIC ACTUATOR WITH ARCUATE EXPANSIBLE CHAMBERS [75] Inventor: Carl W. Kaesemeyer, Cincinnati,

Ohio

[73] Assignee: Cincinnati Milacron Inc., Cincinnati, Ohio [22] Filed: Dec. 15, 1971 [21] Appl. No.: 208,133

[52] U.S. Cl. ..92/66, 92/118, 91/186 [51] Int. Cl ..F01b 15/04 [58] Field 0fSearcl1.91/186,177, 176, 216 R, 216 B, 91/210, 211, 212, 213, 214, 215; 92/67, 66,

[56] References Cited UNITED STATES PATENTS 2,587,893 3/1952 Pridy et a1. ..9l/l86 3,274,895 9/1966 Hendrickson ..9l/l86 3,605,558 9/1971 Leclerco ..9l/171 FOREIGN PATENTS OR APPLICATIONS 16,329 2/1906 Norway ..9 H216 R Primary Examiner--Paul E. Maslousky Attorney-Howard T. Keiser et al.

[57] ABSTRACT A fluid driving apparatus is contained in one of the ends of two lever arms designed to pivot about a common fulcrum point. The driving apparatus comprises a piston limited to move in a direction perpendicular to its axis, an arcuate expansible chamber in each of the lever arms, wherein each chamber is designed to receive one end of the piston, means for providing fluidic communication between the chambers and means for supplying fluid under pressure to the chambers thereby expanding said chambers and applying a force to the lever arms.

5 Claims, 4 Drawing Figures HYDRAULIC ACTUATOR WITH ARCUATE EXPANSIBLE CHAMBERS BACKGROUND OF THE INVENTION In recent years, developments have occurred in the metalworking industry that have placed demands for higher torque drives to cutting tools which are fed in opposition to the forces generated by rotating workpieces. This is particularly true with the introduction of high efficiency turning techniques.

When high efficiency turning is utilized the forces required to feed a cutting tool into a rotating workpiece with a single plunge out have scaled upward to the extent where conventional driving mechanisms are no longer adequate for many operations. This is particularly true when a plurality of cutting tools are placed around the periphery of a rotating workpiece and are fed simultaneously into the workpiece to remove excess metal with a single plunge cut. Such a system is more particularly described in the co-pending application of C. W. Kaesemeyer, assigned to the present assignee, entitled Improved Multi-plunge Turning Apparatus, and filed on the same day as the present application.

As will be apparent from the ensuing detailed description, the present invention provides a tool driving means capable of transmitting very high driving force to a plurality of tools entering a rotating workpiece at diametrically opposing intervals.

SUMMARY OF THE INVENTION The device of this invention is most particularly used in a machine requiring equal forces to be applied to a plurality of tools entering a rotating workpiece at diametrically opposing intervals.

A unique hydraulic actuator is used to provide a work driver capable of generating an arcuate movement of plurality of working members about a remote pivot point. The apparatus includes a set of arcuate expansible chambers, one for each working member, the radius of the arc corresponding to the swing radius of the working members. Each of the chambers is designed to accept one end of a piston. The piston moves only in the direction of the swing radius as hydraulic fluid is introduced under pressure to generate motion of the expansible chambers with respect to one another.

THE DRAWINGS FIG. 1 is a sectional view showing the preferred embodiment of the invention in the ultimate closed position.

FIG. 2 is a sectional view showing the preferred embodiment of the invention in the ultimate open position.

FIG. 3 is a sectional view taken along lines 3--3 of FIG. 1.

FIG. 4 is a sectional view taken along lines 4-4 of FIG. 2.

DETAILED DESCRIPTION Referring first to FIGS. 1 and 2, the piston extends into two separate expansible chambers 12 and 14. O-rings 16a and 16b, or similar articles, are supplied to seal the gaps between the piston 10 and their respective chamber walls from fluid leakage. A channel 18 in piston 10 provides fluidic communication between chambers 12 and 14. A fluid supply line 20 provides hydraulic fluid under pressure to the chamber 12 and through the channel 18 to chamber 14. Each of the chambers 12 and 14 are contained in independent lever arms 22 and 24, respectively. The levers 22 and 24 have common fulcrum point 26 at which they are rotatably secured to shaft 66. Shaft 66 is secured between support walls 62 and 64 (best seen in FIG. 4).

The end of each of the levers 22 and 24 in which chambers 12 and 14 are located, respectively, shall for convenience be referred to as the driving end. The end of each of the levers opposite the driving end carries a set of cutting tools 28 and 30 respectively. This arm of each lever shall be referred to as the working end. A workpiece 32, here shown in phantom, is carried between centers, not shown. As the workpiece 32 is rotated on the centers, the cutting tools 28 and 30 simultaneously close in on the workpiece 32 to effect a plunge turning operation such as described in the aforementioned co-pending application. It should be noted that the apparatus therein described requires a driving mechanism generating a high driving force while requiring close tolerances on the cutting tool movement. The hydraulic actuator of the piston 10, the chambers 12 and 14 and hydraulic fluid supply 20, provides one means suitable to achieve that end.

The expansible chambers 12 and 14 together with the piston 10 and the gears 44 and 46 provide a unique apparatus for generating an arcuate movement of two levers about a remote pivot point 26. In order to maintain contact between the O-rings 16a and 16b, and the walls of chambers 12 and 14, the chambers must be constructed along an arcuate path having the same radius as the swing radius of the lever arms 22 and 24 about the pivot point 26. The swing radius 75 is determined by measuring the distance between the pivot point 26 and the axis 27 of the piston 10 when the lever arms are in the ultimate closed position shown in FIG. 1.

The end-points 27a and 27b of the piston axis must always correspond to a line passing through the center of their respective chambers. Thus, if the piston 10 is held in a horizontal plane, allowed to move only in a direction parallel to the radius 75, the expansible chambers 12 and 14 must be constructed in such a manner that the diameters a and 80b of the heads of the piston 10 always correspond to the cross-sectional diameter of the chambers 12 and 14 respectively. In order that the optimum section of the arc struck by radius 75, that section most nearly perpendicular to the line 75 as shown, may be utilized in construction of the chambers 12 and 14, it is necessary to transpose the pivotal center 26 to a point corresponding with the mid-point of the depth of stroke of each expansible chamber. Thus, when the depth of stroke is determined, dependent on work requirements, the mid-point is struck as indicated by the bisectors 73a and 73b through the lines 69a and 69b indicating depth of stroke for each cylinder. A perpendicular line 72, parallel to the axis 27 of the piston 10, passes through the pivot point 26. The intersection of lines 73a and 72 constitute the transposed center 76a for the construction of expansible chamber 12. The transposed center 76b is generated by the intersection of bisector line 73b and line 72. If a radius 750 and a radius 75b, each identical to the radius 75 is struck from the respective transposed center 76a and 76 b, respectively, these arcs constitutes the center of the respective expansible chambers. The expansible chambers 12 and 14 are then constructed in a manner such that the outer walls, as in dicated by the section plane illustrated in FIGS. 1 and 2, correspond to a number of concentric circles. The difference in the radii 74a and 78a is equal to the diameter 80a of the piston 10. In a like manner the radius 78b is less than the radius 74b by the diameter 80b of the piston 10.

In FIG. 2, the distance between the axis 27 of the piston and the arc struck by radius 75 indicates the amount of horizontal movement necessary by the piston 10 of the transposed centers 76a and 76b are used to construct the expansible chambers 12 and 14. It should be noted that this distance would change with relocation of these centers. It is, therefore, critical that the distance between the center 26 and 76a be held within a close tolerance with respect to the distance between the center 26 and the center 76b in order that both expansible chamber 12 and 14 require this same amount of lateral movement by the piston 10 when the lever arms 22 and 24 move through their entire stroke.

One manner of manufacturing the expansible chambers 12 and 14 to assure the required tolerance is to use a typical fly cutter on a horizontal boring machine with a rotary table. The lever 22 then becomes a workpiece and is mounted so that it will rotate about the center 76a on the rotary table. The cutter is horizontally positioned so that when the mid-point of the stroke is reached, the face of the cutter is parallel and corresponds to a line extended to the face of the cutter from the center point 76a. Then, as the cutter is' rotated, the lever arm 22 is fed into the cutter to construct the chamber 12. When this is done, the lever 24 is mounted on the table in a like manner to rotate about the center 76b and the process is repeated.

In order to provide lateral movement of the piston 10 and restrain vertical movement, an extension 34 is secured to the piston 10 by a suitable means such as welding to form an integral part thereof. The wide tab 36 of the extensionslidably fits between the shafts 38 and 40 which rotatably carry the aforementioned gears 44 and 46 as best shown in FIG. 3. The tab 36 is designed to slide without respect to the relative rotation of either the shaft 38 or 40. g

The gears 44 and 46 provide a means for insuring synchronized movement of the expansible chambers 12 and 14. Meshed with the teeth on gear 44, rotatably mounted on drive shaft 38, are the teeth on gear 46. Gear 46 is rotatably mounted between walls 62 and 64 on shaft 40. Curvilinear racks 45 and 47 are secured to the rear portion of the driving ends of each lever and are engaged with the gears 44 and 46, respectively. Thus, as hydraulic fluid is supplied under pressure to chambers 12 and 14 through supply line 20, the expansible chambers are forced apart to the position shown in FIG. 1. The drive shaft 38 of the gears 44 and 46 is free to rotate during this phase, and the gears 44 and 46 together with the curvilinear racks 45 and 47 require that the lever arms 22 and 24 move simultaneously through the same angle. Thus, the cutting tools 28 and 30 penetrate the rotating workpiece 32 at the same feed rate. It should be noted in an application not requiring synchronized movement of the chambers 12 and 14 the gears 44 and 46 need not be employed in this manner.

The gears 44 and 46 of the preferred embodiment also are utilized as a means for retracting the cutting tools from the workpiece 32 to the position shown in FIG. 2. The gears are driven by drive shaft 38 which is rotatably secured between the support walls 62 and 64 and driven in the usual manner. After the system has reached the position illustrated in FIG. I, the supply line 20 is opened to exhaust and the drive shaft 38 is rotated clockwise, causing a like rotation by gear 44 and a counter clockwise rotation in gear 46. This closes the chambers 12 and 14 and withdraws the cutting tools 28 and 30 from the workpiece 32 as shown in FIG. 2. It should be understood that the tools 28 and 30 could also be retracted by other means, for example, a vacuum line used alternatively with supply line 20. This means was not employed herein in order to keep the pressure in the system at no less than one atmosphere to insure a minimum of contaminants entering the fluid system.

Positive stop 42 is provided to limit the movement of 1 the levers thus keeping the head diameters a and 80b of piston It} in contact with the chamber walls. Due to the intermeshing of the gears 44, 46 and the curvilinear racks 45 and 47 on the lever arms 22 and 24, only one positive stop 42 is necessary for limiting the movement of both levers 22 and 24.

FIG. 4 is a section view taken along lines 44 of FIG. 2. It can be seen that the lever 22 and the lever 24 are both provided with ribs that are alternately spaced thus permitting the levers to move through a greater range and yet provide bearing surfaces for the gears 44 and 46 to limit the size of the gears. The ribs 48, 50 and 52 of lever 22 are designed to fit between the ribs 54, 56 and 58 of the lever 24. This arrangement permits the gears 44 and 46 to be of a smaller diameter and still be engaged in the teeth on the curvilinear racks 45 and 47 of the lever arms. It further provides an increased range of movement of the lever arms 22 and 24 by permitting the arms to pass each other without interference. As illustrated in FIG. 4, the gap provides clearance between the ribs 50 and 56 for the passage of the extension 34. As shown in FIG. 3, the gear 44 is actually comprised of components 44a and 44b. Each component is secured by a key to the drive shaft 38. In this manner clearance is provided for the extension 34. Gear 46 is comprised of components 46a and 46b secured to shaft 40 in a similar manner.

It should be understood that the foregoing is for illustrative purposes only and is not intended to limit the spirit of the invention nor the scope of the appended claims.

What is claimed is:

1. In a system having two lever arms, each of said lever arms pivotally secured to a common fulcrum point, and each of said lever arms having a working end 6 c. a first arcuate expansible chamber suited to a. a first curvilinear rack secured to the driving end receive one end of said piston and secured to the of said one lever arm; dri g end of Said 0118 level b. a first annular gear, rotatably supported, and en- (1. a second arcuate expansible chamber suited to gaged i h id fir t curvilinear rack;

receive the other end of said piston and secured to 5 the driving end of said other lever arm;

e. means for providing fluidic communication between said first and second arcuate expansible chambers; and

f. means for supplying fluid under pressure to said ar- 10 cuate expansible chambers thereby expanding said chambers and applying a working force to the working end of each of said lever arms.

c. a second annular gear, rotatably supported, and

engaged with said first annular gear; and d. a second curvilinear rack secured to the driving end of said other lever arm and engaged with said second annular gear. 4. The apparatus of claim 1 wherein said means for providing fluidic communication comprises a hollow, through channel contained in said piston.

2. The apparatus of claim 1 wherein there further is The apparatus of the clam] 1 wherem sald flmd provided a means for synchronizing the movement of P meajns i further, i s for said first and second arcuate chambers with respect to w'thdrawmg Sald fluid from Sald cham ers t ere y id piston, tracting said chambers.

3. The apparatus of claim 2 further comprising: 

1. In a system having two lever arms, each of said lever arms pivotally secured to a common fulcrum point, and each of said lever arms having a working end and a driving end, a fluid driving apparatus contained in said driving end, said apparatus comprising: a. a piston; b. means for limiting the movement of the piston to a direction perpendicular to the axis of said piston; c. a first arcuate expansible chamber suited to receive one end of said piston and secured to the driving end of said one lever arm; d. a second arcuate expansible chamber suited to receive the other end of said piston and secured to the driving end of said other lever arm; e. means for providing fluidic communication between said first and second arcuate expansible chambers; and f. means for supplying fluid under pressure to said arcuate expansible chambers thereby expanding said chambers and applying a working force to the working end of each of said lever arms.
 2. The apparatus of claim 1 wherein there further is provided a means for synchronizing the movement of said first and second arcuate chambers with respect to said piston.
 3. The apparatus of claim 2 further comprising: a. a first curvilinear rack secured to the driving end of said one lever arm; b. a first annular gear, rotatably supported, and engaged with said first curvilinear rack; c. a second annular gear, rotatably supported, and engaged with said first annular gear; and d. a second curvilinear rack secured to the driving end of said other lever arm and engaged with said second annular gear.
 4. The apparatus of claim 1 wherein said means for providing fluidic communication comprises a hollow, through channel contained in said piston.
 5. The apparatus of the claim 1 wherein said fluid supplying means is further alternatively used for withdrawing said fluid from said chambers thereby contracting said chambers. 